Jonathan Tyler was elected as the first chairman of the party in 1976,[1] and Jonathon Porritt became a prominent member. That same year the Leader Tony Whittaker and National Secretary Lesley Whittaker (founder members of the original PEOPLE party) greatly reduced their involvement with the party.[2] At the 1977 Party Conference in Birmingham, the Party's first constitution was ratified and Jonathon Porritt was elected to the Ecology Party National Executive Committee (NEC). Porritt would become the Party's most significant public figure, working, with David Fleming, "to provide the Party with an attractive image and effective organization".

With Porritt gaining increasing prominence and an election manifesto called The Real Alternative, the Ecology Party fielded 53 candidates in the 1979 General Election, entitling them to radio and television election broadcasts. Though many considered this a gamble, the plan, encouraged by Porritt, worked, as the Party received 39,918 votes (an average of 1.5%) and membership jumped tenfold from around 500 to 5,000 or more. This, Derek Wall notes, meant that the Ecology Party "became the fourth Party in UK politics, ahead of the National Front and Socialist Unity".[3]

Following this electoral success, the party introduced annual spring conferences to accompany autumn conferences, and a process of building up a large compendium of policies began, culminated in today’s Policies for a Sustainable Society (which encompasses around 124 520 words[4]). At the same time, according to Wall, "the Post-1968 generation" began to join the Party, advocating non-violent direct action as an important element of the Ecology Party vision outside of electoral politics. This manifested itself in an apparent "decentralist faction" who gained ground within the Party, leading to Party Conference stripping the Executive of powers and rejecting the election of a single leader. The new generation was in evidence in the first 'Summer Green Gathering' in July 1980, the action of Ecology Party CND (later Green CND), and the Greenham Common camp. The Party also became increasingly feminist.[3]